Very long computations : it is advised to start iterate
(for instance 10000 time steps...) at the end of seance (near 18h), and
to enable Autosave (File->Write->Autosave).

The Implicit VOF Scheme is hard to set : the calculation
converge, but the solution is not very physic.

In theory, the VOF model has to be use with auto-adaptative
meshes. But the way to adapt a mesh with Fluent can't be "auto", so you
have two choice : adapting your self every n time-steps, or doing an initial
mesh with little cells (typically, for one bubble 100 cells).